The present invention relates to a novel sealant composition and to a method for preparing the sealant composition. The sealant composition of the invention is especially favorable for sealing vehicle parts, such as car parts. For example, when filled inside the weather strip of a vehicle, the sealant composition seals the gap between the trim and the plate flange when the plate flange is inserted inside the trim.
The embodiment described herein uses a weather strip for a trunk lid; however, the invention is not limited to this embodiment. The sealant composition of the invention is applicable to any other weather strips, such as lift gates. The sealant composition can also be used for other purposes, such as sealing plate-to-plate gaps or plate-to-rubber gaps.
2. Description of the Related Art
A general example of an ordinary sealant applied to a trunk lid weather strip is described with reference to FIG. 1 and FIG. 2.
FIG. 2 is a sectional view of the cross section of FIG. 1 as cut along line 2--2. In FIG. 2, the weather strip 12 comprises a trim 14, a hollow seal 16 and a seal lip 18. The trim 14 is provided with two pairs of pinching lips 20 and 22 therein, and a plate insert 24 is embedded in the trim 14. The plate insert 24 is for retaining the shape of the trim 14 and for ensuring the pinching force of the lips 20 and 22.
A sealant S is charged in the bottom of the trim 14, and the weather strip 12 is fitted to the plate flange 26 of the trunk via the trim 14. In this condition, an end portion of the plate flange 26 is inserted into the sealant S. In FIG. 2, 27 (dotted line) is a trunk lid.
The sealant ensures the plate flange is rust-proof and seals the inside of the weather strip trim well.
Table 1 shows one conventional sealant composition applicable to the site illustrated in FIGS. 1 and 2.
The conventional sealant composition (listed as the comparative example in Table 1) indispensably requires an organic solvent (for example, kerosene) to dissolve the base component, butyl rubber, to produce a predetermined viscosity.
Typical organic solvents for that purpose are generally toxic and volatile, and have the following problems:
(1) The organic solvents require special care to ensure safe working environments in the process of sealant production and coating. Organic solvents can also cause global environment protection problems, thus requiring the release (vaporization) of solvents from sealants to be minimized as much as possible.
(2) Fresh sealants just after production are tacky and stringing. Therefore, in charging the sealants in a desired site, the sealants often adhere to other parts, thus adversely affecting the charging of the sealants. In addition, the fluidity of the sealants is high. Therefore, after the sealant has been charged inside the trim, it is impossible to turn the trim upside down so as to continuously fit the weather strip to the plate flange. On the other hand, if the trim has been left too long after charging with the sealant, the organic solvent vaporizes from the sealant and the viscosity of the sealant increases. In that condition, the load for inserting the plate flange into the trim increases, and this increased load has negative influences on the weather strip fitting operation.